Tort pickguards are interesting!
Spitfire are the only guys on the block making period accurate tort. This comes down to the volatility of the materials involved apparently.
Saying that, most tort pickguards are wrong for a number of reasons. A '60s tort pickguard has a thin black ply, whereas every modern pickguard has equally thick white and black layers under the tort. Vintage tort is also a thick slab on top of the upper white layer, whereas modern tort pickguards typically have a thin layer. When you see a true '60s pickguard the top slab of tort is thick enough for you to get a proper sideways look through it on the bevel.
The tort effect in a '60s pickguard is fuzzier than in a modern tort pickguard. The colours blend into each other at the edges.
Finally vintage pickguards have a 30 degree bevel, versus a modern 45 degree pitch. On aged pickguards this bevel becomes even more relaxed, down to 25 degrees or so, as the celluloid tort layer shrinks back. In the detailed photo here you can see how each layer subtly blends into the next, the black layer is thin and the tort layer is thick! There is also tooling chatter all over the bevel. The white layers aren't perfectly white either. At a guess the bottom layer is parchment white and the top layer is 'mint', but they aren't solid, consistent colours.
My go-to mod for pickguards is to increase the bevel to 30 degrees.
This is an Amazon 'Floer' pickguard I paid about £15 for (in a pack of two!). The red and yellow layer is pretty nice, albeit thinner than a vintage pickguard. I've decreased the pitch of the bevel to around 30 degrees. The white layer is too starkly white and the black layer is too thick.
Oddly enough the '60s Fender used a different tort on '60s Mustang basses. The red is a lot redder, and there isn't a lower white layer. The layers are tort/white/black with a thick black layer.
Most Tort Fender now make is too dark (though apparently '60s tort started out dark and fades over time). There is no 'movement' within this tort. The dark bits are dark, the light bits are like white/cream blobs, and there isn't much interaction between the two. Conversely Fender Japan used a tomato soup red tort for the longest time with no real variance in shade in it.
This is what '60s tort is all about, per my description above:
I've bought a lot of tort pickguards! Here are some, and the major issues with each:
Cheap Ebay. Too much pink in the mix, some very dark spots and random almost white/cream spots. I increased the bevel on this pickguard to vintage specs.
Less cheap Ebay, from Singapore! Printed tort effect with visible DPI. A photo of tort laminated onto a 3-ply white pickguard. Again added vintage bevel, but very overpriced for a cheap unit.
Dark celluloid tort. Again quite cheap on Amazon. Looks like a Gila Monster. Good if you want a '70s Japanese 'Lawsuit' vibe as they used black/yellow big-swirl tort like this.
Finally, here's some more I wasted money on!
Top right is brown, 'celluloid' (allegedly) guard imported to the UK by somebody on the Basschat forum. The brown layer was thin, lifeless looking and shrinking rapidly around all the edges and routes. Note that it is deep brown, with small cream spots here and there. Check the second Gila Monster tort pickguard bottom left, and second pinky-tort pickguard bottom right.
